全文获取类型
收费全文 | 289篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 63篇 |
金属工艺 | 5篇 |
机械仪表 | 18篇 |
建筑科学 | 9篇 |
能源动力 | 31篇 |
轻工业 | 20篇 |
水利工程 | 6篇 |
无线电 | 30篇 |
一般工业技术 | 80篇 |
冶金工业 | 8篇 |
自动化技术 | 33篇 |
出版年
2024年 | 5篇 |
2023年 | 3篇 |
2022年 | 17篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 14篇 |
2017年 | 20篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 50篇 |
2012年 | 16篇 |
2011年 | 24篇 |
2010年 | 15篇 |
2009年 | 23篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 4篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有303条查询结果,搜索用时 46 毫秒
51.
Rafidah Razuan Nur Aimi Jani Mohamad Kamal Harun Mahesh Kumar Talari 《Transactions of the Indian Institute of Metals》2013,66(4):309-312
Properties of pure metals can be enhanced by alloying with other metallic or non-metallic elements according to the need. However, as multiple alloying elements in an alloy may lead to the formation of many intermetallic compounds with complex microstructures and poor mechanical properties, new types of metallic alloys called high entropy alloys with at least five elements with equimolar ratios were developed. In this study, FeNiAlCuCrTi x Nb y (x, y = 0, 0.5, 1.0, 1.5) alloys have been prepared using Ar arc melting technique. Microstructural studies using scanning electron microscope and XRD showed that Ti addition promoted secondary BCC2 phase whereas, Nb acted as FCC stabilizer. Samples with combined Nb and Ti addition showed FCC1 and FCC2 structure with Nb-rich FCC2 dendritic phase as dominant phase. Though, individual Nb and Ti additions have resulted in increased hardness, combined additions have resulted in highest hardness of 797 HV under 1 kg load. 相似文献
52.
Samiaah M. Hassen Al-Tmeemy Hamzah Abdul- Rahman Zakaria Harun 《International Journal of Project Management》2012
While conforming on the findings of prior researches regarding quality cost system in building companies, current research successfully illustrates the contractors' perceptions on the importance of the quality cost system and the barriers that may constrain the implementation of the system for recording and collecting quality cost data. A postal and email surveys were undertaken on Malaysian building companies, focusing on the benefits and difficulties associated with the implementation of quality cost system. Statistical analyses based on Chi-Squared test and Relative Importance Index techniques were used to investigate the significance of the findings and determine the relative importance of the factors. The most important benefit of measuring quality costs is “getting management attention and increase quality awareness” as perceived by the sample of the study. The possible barriers that may affect the management's decision to implement quality cost system are identified and grouped into three categories, which are culture and knowledge; system; and company. The study suggests that the level of the site staff's knowledge should be as important as that of the management to successfully collect and record quality costs data. The findings of this research will raise the level of awareness and sensitize managers and those involved with building industry about the importance of quality cost system and collecting quality costs data. 相似文献
53.
MA Harun RJ Veeneklaas M Van Kampen M Mabasso 《Canadian Metallurgical Quarterly》1998,77(9):1280-1286
A breeding biology study of a genetically unselected variety of Muscovy duck Cairina moschata was conducted in an experimental duck unit in Maputo, Mozambique (25 degrees 58' S, 32 degrees 35' E), to gain insight into factors affecting hatchability during natural incubation. Nesting and incubation behaviors were recorded by daily nest visits. Of 1,338 nests investigated, 70% were incubated until hatching. In 23% of the incubated nests, eggs were laid by more than one duck in the same nest, indicated as dump nests. Artificial dump nests (15% of the incubated nests) were created by adding eggs (690 eggs) from nests abandoned by the duck before incubation had started. A total of 37% of the incubated nests contained eggs that were laid after the onset of incubation (nonterm eggs). Similar hatching rate was found between ducks raised in parks with or without access to swimming water. No significant difference was found in hatchability between normal (0.76) and dump nests (0.77). Artificial dump nests showed higher hatching rates than nests containing nonterm eggs. Dump nesting appears to be a reproductive strategy used by the Muscovy duck to enhance duckling production. Hatching rate was strongly influenced by the length of laying period (period between the ovoposition of the first egg until the onset of incubation) and reproduction cycle (laying period and incubation period). Hatchability was higher for clutches with a shorter reproduction cycle. It is concluded that nesting behavior of the domesticated Muscovy duck is similar to that of its wild ancestor. 相似文献
54.
55.
Razif Harun Manjinder Singh Gareth M. Forde Michael K. Danquah 《Renewable & Sustainable Energy Reviews》2010,14(3):1037-1047
Microalgae biotechnology has recently emerged into the lime light owing to numerous consumer products that can be harnessed from microalgae. Product portfolio stretches from straightforward biomass production for food and animal feed to valuable products extracted from microalgal biomass, including triglycerides which can be converted into biodiesel. For most of these applications, the production process is moderately economically viable and the market is developing. Considering the enormous biodiversity of microalgae and recent developments in genetic and metabolic engineering, this group of organisms represents one of the most promising sources for new products and applications. With the development of detailed culture and screening techniques, microalgal biotechnology can meet the high demands of food, energy and pharmaceutical industries. This review article discusses the technology and production platforms for development and creation of different valuable consumer products from microalgal biomass. 相似文献
56.
A Bi2O3-based erbium-doped fiber (Bi-EDF) ring laser with a 70?nm tunable range is demonstrated with a 49?cm long Bi-EDF in which tuning range can be extended to larger than 100?nm using an optical switch to alter the length of Bi-EDF in the laser cavity. With an extinction ratio of better than 60?dB throughout the entire tuning range, the measured FWHM of laser lines are measured to be 0.09?nm. In addition, the common amplification parameters are measured and studied in detail for various pumping configurations. 相似文献
57.
In this study, for the first time, the effect of Nickel (Ni) additive on Magnesium oxide (MgO) thin films produced by using successive ionic layer adsorption and reaction technique (SILAR) was investigated. Absorption, photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) measurements were executed to examine how the optical, structural and morphological properties of the samples were affected by the addition of Ni. In the absorption analysis, it was noted that the band gaps of the MgO samples decreased from 4 eV to 3.5 eV with the increase of Ni dopant concentrations. Also, the transmittance values of MgO nanostructures decreases with the increase of Ni contribution, and in the same way, the reflection measurements show that the reflection of MgO decreases with the increase of Ni doping. PL measurements revealed that the fabricated structures radiate around 410 nm and 730 nm. According to XRD measurements, besides the cubic structure of the samples, NiO formations were detected inside the MgO thin film samples due to the increase in Ni dopant. XPS measurements have proven the presence of Ni doping in MgO. SEM measurements showed that all samples exhibited nanowall structure. All these results demonstrate that Ni doping on MgO thin films can be achieved by using SILAR deposition technique. 相似文献
58.
Kinetic and transport effects on enzymatic biocatalysis resulting from the PEGylation of cofactors 下载免费PDF全文
The utilization of cofactor‐dependent redox enzymes in bioprocess technologies requires low cost cofactor regeneration methods. PEGylated NAD(H) (PEG‐NAD(H)) has been utilized in enzyme membrane reactors as a means to recover the cofactor; however, there is a lack of understanding of the effect of PEGylation on enzymatic activity, especially on the relationship between biocatalysis and transport phenomena. To explore this further, two redox enzymes (formate dehydrogenase (FDH) from Saccharomyces cerevisiae and NAD(H)‐dependent d ‐lactate dehydrogenase (nLDH) from Escherichia coli) have been chosen and the kinetic effects caused by cofactor modifications (with PEG of three different chain lengths) have been investigated. The PEGylation did not impact the cofactor dissociation constants and mass transfer was not the rate‐limiting step in biocatalysis for either enzyme. However, the PEG chain length had different impacts on the formation of enzyme/cofactor and/or enzyme/cofactor/substrate ternary complexes for the enzymes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 12–17, 2018 相似文献
59.
Mohd Hafiz Jali Hazli Rafis Abdul Rahim Md Ashadi Md Johari Maslinda Mat Sharif Siti Halma Johari Siddharth Thokchom Habibah Mohame Moh Yasin Sulaiman Wadi Harun 《光电子快报》2021,17(5):298-301
In this letter, a humidity sensor is demonstrated by applying a whispering gallery mode (WGM) from a microsphere resonator onto the ZnO nanorods coated glass surface. The diameter of the microsphere was 234 µm and the glass surface was coated with ZnO nanorods using the hydrothermal method at growth duration of 12 h. A significant response to humidity level ranging from 35%RH to 85%RH has been observed with the sensitivity of 0.014 2 nm/%RH. The proposed humidity sensor has successfully employed to enhance interaction between the whispering gallery mode evanescent and surrounds analyte with the assistance of ZnO nanorods coated glass. 相似文献
60.
Ahmad H. A. Rosol Afiq A. A. Jafry Norrima Mokhtar Moh Yasin Sulaiman Wadi Harun 《光电子快报》2021,17(8):449-453
Passively Q-switched thulium doped fiber laser (TDFL) has been successfully demonstrated using gold nanoparticles (GNPs), which were embedded into polyvinyl alcohol as saturable absorber (SA). The stable self-starting Q-switched laser was generated to operate at 1 891 nm when a tiny piece of the prepared film was slot in between two fiber ferrules and incorporated into the laser cavity. The repetition rate can be adjusted from 48.54 kHz to 49.64 kHz while the pulse width decreased from 3.52 μs to 2.38 μs with the increase of 1 550 nm pump power from 840 mW to 930 mW. The corresponding pump power output power linearly increased from 3.62 mW to 6.3 mW with a slope efficiency of 2.53%. The maximum peak power and pulse energy were recorded at about 39 mW and 0.12 µJ, respectively at pump power of 930 mW. The Q-switching operation was caused by the surface plasmon resonance absorption of GNPs. 相似文献